A registered nurse, Scoggins was supervising West’s post-surgery care with West’s assistant and a friend when, according to a source familiar with the situation, he left the house to attend a baby shower the day after West underwent breast reduction and liposuction last Nov. 10. West died that evening at a Los Angeles hospital.

At the time, the death of the rapper’s mother was described by a family spokesman as “the result of complications from a cosmetic surgical procedure,” a statement that placed intense scrutiny on West’s surgeon, Dr. Jan Adams.

But last January, a Los Angeles coroner ruled that West died of “multiple post-operative factors,” effectively clearing Dr. Adams of responsibility.

In this new development, an investigator with the California Department of Consumer Affairs has issued subpoenas asking individuals “to testify in the matter of the investigation of Stephan Scoggins,” a source tells PEOPLE.

WEST’S CONDITION

The California Department of Consumer Affairs represents the California Board of Registered Nursing, of which Scoggins is a member. A public information officer for the consumer affairs department, Russ Heimerich, told PEOPLE: “We do not comment on ongoing investigations.” Scoggins – who risks losing his nursing license if complaints against him are substantiated – could not be reached for comment.

According to an autopsy report, a heavily-bandaged West was able to walk out of the medical facility after nearly five and a half hours of surgery last November. The report further stated, “[West] opted to return to her home for care even though she was advised that she receive post-operative care at another facility.”

That night, West took Vicodin for pain, slept and felt better in the morning. Later in the day, a source tells PEOPLE, Scoggins left West’s home to attend a baby shower and was unreachable when her condition worsened. According to the autopsy report, West experienced pain, a sore throat and tightening in her chest before collapsing in the early evening. A friend at the house called 911 and West was taken to a hospital, where she was pronounced dead in the emergency room.

The source also says investigators are looking into the possibility that Scoggins administered too much Vicodin in a short period of time. In an interview with PEOPLE last year, Dr. Adams said he and Scoggins discussed West’s care briefly, but did not establish a detailed plan. “There s no set regimen, like you need to do this and this,” he said.

A rep for Kanye West did not return repeated messages seeking comment.